1. Field of the Invention
This application relates to a method and device for preventing damage from freezing water to a ball-type valve. More particularly, but not by way of limitation, the disclosed invention provides a removable concave plug with a relatively thin-walled floor with scored areas and a thick-walled section on the valve body at a location opposite to the removable concave plug. The scored areas of the plug act create a sacrificial surface that gives away under the pressure from water expansion due to freezing.
2. Discussion of Known Art
Ball valves have been widely used for controlling the flow of various types of fluids under various conditions. Their use has been favored due to the simplicity of the valve, which in its most basic form consist of a ball with a passage that can be rotated. The rotation allows opening of the valve through the alignment of the passage with the valve inlet and the valve outlet, and then closing the valve by rotating the passage to a position where the passage is no longer exposed to the valve inlet. The simplicity and reliability of ball valves has made them very popular as part of lawn sprinkler systems. However, the passage in the ball of a ball valve makes the valve vulnerable to damage due to freezing of water trapped in the passage during the winter months.
Efforts to alleviate the possibility of damage from freezing include the device disclosed in European Patent Application 2110589 to Cagnacci, which provides a receptacle that is positioned below the ball of the ball valve. The receptacle collects moisture that may lead to damage from freezing of the valve. An important problem associated with the Cagnacci device is that based on observations of ball valves damaged by freezing, the damage due to freezing is consistently found on the side of the ball valve body. See accompanying FIG. 10. It is thus concluded that it is the freezing water that is trapped in the passage through the valve that causes the damage to the ball valve. A possible solution to this problem would be to simply provide a device with drainage ports, such as the valve shown in U.S. Pat. No. 4,027,698 to Weinhold, which uses a drainage to remove the water trapped in the valve body and thus obviate the problem of freezing.
A similar approach to Weinfold's approach is found in U.S. Pat. No. 4,718,444 to Boelte, which discloses the use drainage ports that align with the passage of the ball when the ball is in the closed position. A problem with the provision of a drainage port or valve to drain liquids from the ball passage when the valve is in the closed position is that the homeowner often forgets to open the drainage port before freezing occurs, and thus the valve is damaged during the first freezing of the fall or unexpected freezing in the spring.
U.S. Patent Application Publication No. 2008/0258092 to Pettinaroli et al., which simply exposes the ball passage to a side opening on the ball valve, and the side opening is then capped with a female plastic cap that is tethered to a male extension that protrudes from the side of the valve body. A problem with the Pettinaroli et al. approach is that the damage due to freezing is typically a product of neglect or unexpected freezing temperatures in the fall or in the spring. Accordingly the side outlet is likely to be plugged at the time of freezing, making the plug on a side outlet an ineffective solution.
Therefore, a review of known devices reveals that there remains a need for a simple device that supports a concealed hook for hanging ornaments.